US4473313A - Timing control method for controlling reciprocating print head - Google Patents

Timing control method for controlling reciprocating print head Download PDF

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Publication number
US4473313A
US4473313A US06/378,354 US37835482A US4473313A US 4473313 A US4473313 A US 4473313A US 37835482 A US37835482 A US 37835482A US 4473313 A US4473313 A US 4473313A
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Prior art keywords
signal
print head
values
timing control
position signal
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US06/378,354
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Hiroshige Nakano
Atsuhiko Takanashi
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Koki Holdings Co Ltd
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Hitachi Koki Co Ltd
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Assigned to HITACHI KOKI CO., LTD. reassignment HITACHI KOKI CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: NAKANO, HIROSHIGE, TAKANASHI, ATSUHIKO
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J25/00—Actions or mechanisms not otherwise provided for
    • B41J25/001—Mechanisms for bodily moving print heads or carriages parallel to the paper surface
    • B41J25/006—Mechanisms for bodily moving print heads or carriages parallel to the paper surface for oscillating, e.g. page-width print heads provided with counter-balancing means or shock absorbers

Definitions

  • This invention relates to a timing control device in which the position of a moving body which runs at a given speed is detected, and according to the detection signal, a signal for starting an operation with a predetermined delay time is produced.
  • the invention relates to a timing control device in which the position of a moving body such as a print band or a print hammer of a printer, which runs at a given speed, is detected, so that the print hammer is driven at the exact time instant whereby characters are printed correctly.
  • a printer will be described, by way of example, in which a plurality of print hammers 1 having dot elements are arranged in parallel with the print line, and a hammer bank 2 supporting these print hammers 1 is reciprocated across the printing paper, so that during reciprocation the print hammers 1 are selectively operated to print dots at selected positions (FIG. 1).
  • the printer has thirty-four print hammers 1, each of which is reciprocated over a distance corresponding to four characters.
  • a cam device is employed to reciprocate the hammer bank 2.
  • An encoder disc 5 for detecting the positions of the print hammers 1 and a pulley 6 for transmitting the power of a motor 9 are mounted on the cam shaft 4 of the cam device 3.
  • the pulley 6 As the motor 9 rotates, the pulley 6 is turned through a pulley mounted on the output shaft of the motor 9 and a timing belt 7, so that the hammer bank 2 is reciprocated by means of the cam device 3.
  • the locus of motion of the hammer bank 2 is as shown in FIG. 2.
  • Slits 10 are formed in the encoder disc 5 in correspondence to print positions on the locus of motion in FIG. 2.
  • a detector 12 is provided to detect the slits 10. More specifically, when the detector 12 detects a slit 10, it outputs a logical value "1"; and when the detector 12 detects no slit 10, it outputs a logical value "0".
  • an additional slit 11 distinct from the aforementioned slits 10 is formed in the encoder disc 5.
  • the slit 11 is detected by detectors 13 and 14. More specifically, the hammer bank 2 is moved from left to right for the time interval which elapses from the instant when the detector 13 detects the slit 11 to provide a logical value "1" until the detector 14 detects the slit 11 to output a logical value "1". On the other hand, the hammer bank 2 is moved from right to left for the time interval which elapses from the instant the detector 14 detects the slit 11 to output a logical value "1" until the detector 14 detects the slit 11 to provide the logical value "1".
  • the time instant when the slit 10 corresponding to each print position is detected by the detector 12 should be advanced by the flight time T f which elapses from the instant the print hammer 1 is driven until it strikes against the printing paper. This may be achieved by employing a method in which adjustment is accomplished by displacing the detector 12.
  • the locus of motion of the hammer bank 2 is defined by the cam device 3; however, in positioning the cam and the encoder disc 5, it is difficult to position them accurately at the reference position; in other words an error of ⁇ 5 degrees, in general, takes place. Accordingly, the range of adjustment of the detector 12 is more than ⁇ 5 degrees with respect to the detector mounting reference position.
  • the printer four characters are printed by one hammer 1.
  • One character is composed of tweleve dots.
  • the hammer has 48 dot print positions in the lateral direction.
  • the cam of the cam device 3 makes one revolution, the hammer bank 2 accomplishes one reciprocation. That is, when the encoder disc 5 turns through 180 degrees, the hammer bank 2 accomplishes a one-way motion.
  • dots must be printed at 48 dot print positions, and the printing paper must be advanced vertically to the next dot position. The time required for advancing the printing paper converts into an angle of rotation of about 50 degrees of the encoder disc 5.
  • 48 slits 10 are distributed within an angle of about 130 degrees; that is, the slits 10 are provided at angular intervals of about 2.8 degrees. Accordingly, three of four slits 10 are provided within an adjustment range of ⁇ 5 degrees, i.e. in the range of 10 degrees.
  • variable time width of the multivibrator is smaller than the value obtained by converting the angular interval of the slits 10 into time; however, it is not employable in the case where the former is larger than the latter, because the positional correspondence is shifted.
  • the above method is not employable in the case where the range of adjustment is wide, as just described; that is, in the case where three of four slits 10 are included in the range of adjustment.
  • an object of this invention is to eliminate the above-described drawbacks of the prior art, to thereby facilitate adjustment.
  • the detection signal of the slit 10 is written into a memory, and is read out after a predetermined period of time, so that adjustment can be readily achieved.
  • FIG. 1 is a perspective view outlining the arrangement of one example of a printer to which a timing control device according to the invention is applied;
  • FIG. 2 is a diagram showing the locus of motion of a hammer bank in the printer of FIG. 1;
  • FIG. 3 is a block diagram showing one embodiment of this invention.
  • FIGS. 4A and 4B together constitute one timing chart for describing the operation of the circuitry of FIG. 3;
  • FIG. 5 is a block diagram showing one example of the counter clear circuit of FIG. 3.
  • FIGS. 1 and 3-5 One embodiment of this invention will now be described with reference to FIGS. 1 and 3-5.
  • the pulley When a voltage is applied to the motor 9, the pulley is turned via the belt 7. When the speed of the motor 9 becomes constant, the pulley 6 is turned at a constant speed, as is the encoder disc 5.
  • amplifier and waveform shaping circuits 102 and 103 When the detectors 13 and 14 detect the slit 11, amplifier and waveform shaping circuits 102 and 103 output logical values "1", respectively.
  • a set signal is applied to a flip-flop 110, and a bank direction signal i becomes a logical value "1".
  • a reset signal is applied to the flip-flop 110, and the bank direction signal i becomes a logical value "0".
  • the bank direction signal i is used as a control signal for the printer; however, further description of the signal i will be omitted, because it is not concerned with the invention.
  • the waveform shaping circuit 101 When the detector 12 detects the slit 10, the waveform shaping circuit 101 outputs a slit signal f of "1". When no slit 10 is detected, the slit signal f is maintained at "0". The slit signal f is applied to an input terminal of a memory 106.
  • the addresses in the memory 106 are controlled as follows:
  • the content of an address controlling counter 104 for the memory 106 is increased by one (+1) at periods t 0 with a clock signal CLK1 a; that is, the output of the counter 104, namely, a memory address e is increased by +1 every time period t 0 .
  • a counter clear signal d from a counter period circuit 105 is applied to the clear input terminal (CLR) of the counter 104.
  • the period T of the counter clear signal d can be varied as desired. If, for example, the period of the counter clear signal d is set to T'( ⁇ T), then the maximum value of the memory address e becomes N'( ⁇ N). In this case, T' ⁇ t 0 (N'+1).
  • the range of addressable addresses in the memory 106 may be changed by changing the period of the counter clear signal d; the range of addresses being repeatedly and cyclically specified.
  • data written in an address of the memory 106 is read out the next time this address is specified, e.g. after one period T of the counter clear signal d; that is, the data can be outputted with a variable delay time T or T', as desired.
  • Each print hammer 1 has 48 dot print positions.
  • the slits 10 corresponding to these print positions will be designated by reference characters S1, S2, . . . and S48, respectively.
  • the slits 10 are provided at equal angular intervals of 2.8 degrees. Therefore, after the slit S1 is detected with the encoder disc 5 being rotated a slit 10 is detected every 2.8 degrees. That is, the slits S1 through S48 are detected successively at angular intervals of 2.8 degrees.
  • the slit (10) signal f becomes "1".
  • the memory address e of the memory 106 is K 1 .
  • a write pulse (WRT PULSE) b (FIG. 4) is outputted to the memory 106, and the slit signal f at "1" is written in the address K 1 of the memory 106.
  • the clock signal CLK1 a is produced, the content of the counter 104 is increased by +1, and the memory address e becomes (K 1 +1).
  • the slit signal f is maintained at "1", and therefore the logical value "1" is written in subsequent addresses in the memory 106.
  • the memory address e is K' 1 .
  • the slit signal f is maintained at "0", and therefore the logical value "0" is written in the addresses in the memory 106.
  • the slit signal f becomes "1" again.
  • the memory address e of the memory 106 is K 2 (where K 1 ⁇ K 2 ).
  • the write pulse (WRT PULSE) b is produced, so that the slit signal f of logical value "1" is written in address K 2 in the memory 106.
  • the clock signal CLK1 a is outputted, the content of the counter 104 is increased by +1, and the memory address e becomes address (K 2 +1).
  • the content of the counter 104 is increased by +1 whenever the clock pulse CLK1 a is provided as was described above, and the logical value of the slit signal f at that time is written in the memory 106 with the write pulse (WRT PULSE) b.
  • the content of the counter 104 is increased as described above.
  • the counter clear signal d (FIG. 4B) is outputted to clear the content of the counter 104, and therefore the memory address e becomes 0.
  • the memory 106 outputs a memory output signal g which in this case is the logical value "1" of the slit signal f which was written upon the previous detection of the slit S1.
  • the signal is applied to an input terminal D of a flip-flop 107, thus becoming a slit delay signal h of the flip-flop 107.
  • the memory output signal g is at "1" and the output of the flip-flop 107, i.e. the slit delay signal h, is also at "1".
  • the slit S1 has passed, and the next slit S2 is not yet detected. Therefore, for this period, the memory output signal g is at "0", and the slit delay signal h is also at "0".
  • the slit signal f detected by the detector 12 is outputted as a slit delay signal h with a delay time of t 0 ⁇ (N+1) where t 0 is the period of the clock signal CLK1 a and (N+1) is the number of addresses covered by the memory address counter 14 during the period between counter clear signals.
  • the delay time can be changed by changing the value N. Therefore, the delay time can be set as desired.
  • the print hammer 1 can be driven at a desired time instant. That is, adjustment can be readily achieved so that printing is effected at correct print positions.
  • FIG. 5 shows one example of the above-described counter period circuit 105.
  • the circuit 105 is made up of an astable multivibrator 111 having a variable resistor 112 and a capacitor 113 which are externally installed, a differentiation circuit 114 connected to the output terminal of the vibrator 111, and an invertor 115.
  • the period at which the counter clear signal d is generated, namely, the aforementioned value T (or T') can be controlled by changing the resistance of the variable resistor 112.
  • the resistance of the variable resistor 112 is adjusted by referring to a print sample, then adjustment can be achieved so that printing is effected at correct print positions.
  • printer adjustment has been carried out by operating the mechanism section, thus taking a relatively long time.
  • adjustment can be electrically achieved with ease according to the invention, which contributes greatly to a reduction in the number of adjustment steps and to a decrease of the manufacturing cost of the device.

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US06/378,354 1981-05-15 1982-05-14 Timing control method for controlling reciprocating print head Expired - Lifetime US4473313A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP56073826A JPS57188389A (en) 1981-05-15 1981-05-15 Time controller
JP56-73826 1981-05-15

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US4473313A true US4473313A (en) 1984-09-25

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US (1) US4473313A (enrdf_load_stackoverflow)
JP (1) JPS57188389A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5059047A (en) * 1989-02-10 1991-10-22 Hitachi Koki Co., Ltd. Apparatus for controlling reversing duration of hammer bank in shuttle printer
US5572018A (en) * 1993-06-14 1996-11-05 Fanuc Ltd. Method and apparatus to detect absolute position using encoder having a counter clear signal

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5966786U (ja) * 1982-10-28 1984-05-04 加茂　守 卵容器
US4548134A (en) * 1984-02-15 1985-10-22 Hewlett Packard Company Dot image buffer and dot sequence scrambler for dot matrix line printer
JPS6135251A (ja) * 1984-07-28 1986-02-19 Fujitsu Ltd ベルト式ラインプリンタ
JPH0588952U (ja) * 1992-05-15 1993-12-03 日立工機株式会社 ドットプリンタ
US8767027B2 (en) * 2012-10-17 2014-07-01 Printronix, Inc. Preventing coil overheating in line printer hammer banks

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4116567A (en) * 1976-12-22 1978-09-26 Okidata Corporation Printer synchronization control for shuttle having non-uniform velocity
US4284362A (en) * 1979-07-30 1981-08-18 International Business Machines Corp. Printer control logic

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4116567A (en) * 1976-12-22 1978-09-26 Okidata Corporation Printer synchronization control for shuttle having non-uniform velocity
US4284362A (en) * 1979-07-30 1981-08-18 International Business Machines Corp. Printer control logic

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5059047A (en) * 1989-02-10 1991-10-22 Hitachi Koki Co., Ltd. Apparatus for controlling reversing duration of hammer bank in shuttle printer
US5572018A (en) * 1993-06-14 1996-11-05 Fanuc Ltd. Method and apparatus to detect absolute position using encoder having a counter clear signal

Also Published As

Publication number Publication date
JPH0357875B2 (enrdf_load_stackoverflow) 1991-09-03
JPS57188389A (en) 1982-11-19

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